Broken toolchain, or experimental-v4.x sources just broken?

[techflashYT]

I'm trying to build the kernel from the experimental v4.x branch. I was able to get it to work with the following:

• DevkitPPC r27
• Slightly modified wii_defconfig
• iirc a few code patches (I specifically remember needing to add a (weirdly) missing #define in the gcnfb code)

But I've noticed a few issues:

• Framebuffer has an extreme green tint
• When pressing a key on a USB keyboard, it causes a frozen spinlock, the kernel eventually notices it and unfreezes itself, but it's completely unusable

Probably many more, since I can't actually log in due to the USB keyboard issue.

So I was wondering, are these all just expected issues for the 4.x branch, or do I need a more specific toolchain? If so, what toolchain do I need?